1. Field of the Invention
The present invention relates to making it possible for an observer to visually observe a structure of an atomic arrangement three-dimensionally.
2. Description of the Prior Art
A microscope that makes it possible to see a structure of an atomic arrangement directly by an observer""s eyes three-dimensionally is not realized yet. Although an electron microscope gives a projection image of an atomic arrangement, it cannot give a stereoscopic image. Moreover, although a scanning tunneling microscope (STM) can give the concavo-convex image of the atomic arrangement on the front face of a sample, the information about the positional relation between a surface atom and an atom thereunder cannot be given.
As described above, although those conventional microscopes make it possible to observe the structure of an atomic arrangement superficially, it does not make it possible to observe the structure of an atomic arrangement three-dimensionally.
As a method for observing atomic structure three-dimensionally, it is possible that an arrangement among atoms is measured or presumed on the basis of various kinds of observation data, and the result is visualized by computer graphics. However, in this technique, since it is necessary to obtain necessary various observation data in quest of the exact positional relation about all the atoms in an observation part, data processing takes time, and hence real time observation becomes difficult.
An object of the present invention is to provide a method and an apparatus for observing the structure of an atomic arrangement with an observer""s eyes three-dimensionally.
In order to attain the above-described object, a three-dimensional observation method of an atomic arrangement according to the present invention includes: a step of radiating two rays of circularly polarized light, which differ in a rotary direction, to a sample; a step of forming two photoelectron diffraction patterns that differ in a formative direction of photoelectron forward scattering peaks in circular dichroism generated by the radiation; and a step of obtaining, from those photoelectron diffraction patterns, atomic arrangement images having right-handed and left-handed parallactic angles.
Moreover, a microscope according to the present invention that enables three-dimensional observation of an atomic arrangement comprises: circularly polarized light radiation means for radiating a ray of circularly polarized light to a sample to generate photoelectrons; and two-dimensional detection means for detecting a photoelectron diffraction pattern formed by photoelectron forward scattering peaks with circular dichroism generated by the radiated ray of circularly polarized light two-dimensionally.
Furthermore, a stereoscopic measuring method according to the present invention that enables three-dimensional observation of an atomic arrangement includes: a step of radiating two rays of circularly polarized light, which differ in a rotary direction, to a sample; a step of forming two photoelectron diffraction patterns, which differ in a formative direction of the photoelectron forward scattering peaks in circular dichroism generated by the radiation; and a step of picking up those photoelectron diffraction patterns as photographic images corresponding to a parallactic angle of right-handed and left-handed eyes.
Generally, when a ray of light is radiated to a sample, photoelectrons are emitted from an atom (emitting atom), and the emitted photoelectrons are scattered by a surrounding atom (scattering atom), and generate a forward scattering peak in a direction of connecting the emitting atom and the scattering atom. When the ray of light which irradiates a sample is a ray of circularly polarized light, the direction of a forward scattering peak shifts from the direction of connecting the emitting atom and the scattering atom according to the angular momentum which the ray of circularly polarized light has. The direction where this peak shifts depends on whether the rotary direction of the ray of circularly polarized light is the right or the left (namely, right-handed circularly polarized light or left-handed circularly-polarized light). An atomic arrangement can be three-dimensionally observed by associating two images, which are shifted by these rays of circularly polarized light, with respective images when observing objects with both eyes.
Moreover, a magnification by the three-dimensional observation according to the present invention can be set on the basis of the fact that a parallactic angle at the time of observing an object with both eyes and a parallactic angle of the images obtained with using the circular dichroism in photoelectron diffraction differ by a multiple, not depending on an angle.
Circularly polarized light radiation means for radiating a ray of circularly polarized light to a sample makes photoelectrons with different angular momenta emitted by switching a rotary direction of the ray of circularly polarized light with a ray of right-handed circularly polarized light and a ray of left-handed circularly-polarized light. Two (circular dichroism) photoelectron diffraction patterns that the photoelectrons with different angular momenta form correspond to the diffraction patterns when the atomic arrangement is observed from different directions. An object is observable as a stereoscopic image by observing these two diffraction patterns with both eyes, respectively.
Moreover, by launching the ray of circularly polarized light at a shallow angle to a sample, the angle dependency of a parallactic angle comes to be in agreement with an actual thing, and can obtain a stereoscopic image with little distortion. In addition, it is possible to use synchrotron for a right-handed and left-handed circularly polarized light generating apparatus consisting of an electron storage ring and a circularly polarized light undulator, as circularly polarized light radiation means. The observation precision of an atomic arrangement can be improved by radiating to a sample a ray of circularly polarized light with high energy that is obtained in the synchrotron radiation institution xe2x80x9cSPring-8xe2x80x9d which the Japan Atomic Energy Research Institute and the Institute of Physical and Chemical Research in Japan have jointly built.
Two-dimensional electron detection means for two-dimensionally detecting a photoelectron diffraction pattern formed by photoelectron forward scattering peaks with the circular dichroism that is generated by a ray of circularly polarized light radiated by the above-described circularly-polarized light radiation means can display the detected photoelectron diffraction pattern on display means as an image and can also form the pattern as a photographic image. In addition, as the two-dimensional photoelectron detection means, it is simplest to use a two-dimensional display-type analyzer such as a two-dimensional display-type spherical mirror analyzer. Nevertheless, a two-dimensional photoelectron diffraction pattern may be detected by moving a one-dimensional or zero-dimensional (detecting only a certain angle) analyzer, or by combining a one-dimensional or zero-dimensional analyzer and one-dimensional or two-dimensional rotation of a sample.
Moreover, the real time observation of an atomic arrangement is achieved by switching the rays of right-handed and left-handed circularly polarized light by the circularly polarized light radiation means at high speed. At this time, in the two-dimensional photoelectron detection means, two photoelectron diffraction patterns can be detected with synchronization with the switching of rays of circularly polarized light, and the variance of the atomic arrangement can be observed in real time by displaying the image.